$ 100\% - \dfrac{9}{10} = {?} $
Explanation: First get all of the numbers in decimal form. $ 100\% = \dfrac{100}{100} = 1 $ $ -\dfrac{9}{10} = -0.9$ Now we have: $ 1 - 0.9 = {?} $ $ 1 - 0.9 = 0.1 $